An issue that has recently come to the forefront of Clean Water Act (“CWA”) jurisprudence in numerous district courts across the country and which is currently before the Ninth Circuit is whether the discharge of pollutants into groundwater which is hydrologically connected to a surface water is regulated under the CWA. The CWA prohibits discharges from point sources to navigable waters, defined as “waters of the United States,” unless they are in compliance with another provision of the Act, such as the National Pollutant Discharge Elimination System (“NPDES”) permitting program. Whether discharges to groundwater hydrologically connected to a surface water body fall under this prohibition is a question with far-reaching consequences for facilities as varied as coal ash basins, slurry pits, retention ponds, and hydraulic fracturing wastewater ponds, all of which could theoretically be deemed to be in violation of the CWA under this hydrological-connection theory if they leak into groundwater at all.

As a preliminary matter, there is no question that isolated groundwater itself is not a water of the United States regulated under the CWA. First, multiple courts, including several circuit courts of appeals, have held that groundwater is not “waters of the United States.” Second, the legislative history surrounding the CWA indicates clearly that Congress considered setting standards for groundwater or explicitly including it in the NPDES permitting program and decided against such an approach. Finally, in the rule, now stayed by the Sixth Circuit, which EPA and the Army Corps of Engineers promulgated last year defining the term “waters of the United States,” the agencies explicitly stated that they had “never interpreted” groundwater “to be a ‘water of the United States’ under the CWA.” 80 Fed. Reg. 37073.

The hydrological connection issue is not a new one; both the Seventh Circuit in 1994 and the Fifth Circuit in 2001 determined that discharges to groundwater which is hydrologically connected to waters of the United States are not regulated under the CWA or the Oil Pollution Act (“OPA”) (courts have typically interpreted the term “navigable waters” to have the same meaning under both acts). In the past few years, however, the frequency of opinions on this topic has increased, and district courts have been very much split on this issue. Some courts and commentators have dubbed this theory of regulation the “conduit theory,” with the idea being that the groundwater serves as a conduit between the point source and the water of the United States.

Three district courts have recently rejected the conduit theory. In 2014, in Cape Fear River Watch, Inc. v. Duke Energy Progress, Inc., the Eastern District of North Carolina confronted the issue of whether seepage from coal ash basins at one of the defendant’s power plants, alleged to contain contaminants and to carry those contaminants through groundwater into a lake, was a discharge prohibited by the CWA. The court emphatically held that “Congress did not intend for the CWA to extend federal regulatory authority over groundwater, regardless of whether that groundwater is eventually or somehow ‘hydrologically connected’ to navigable surface waters.” As justifications for its holding, it cited the CWA’s dearth of language actually referring to groundwater, its legislative history, and the 2006 Supreme Court case on the meaning of waters of the United States, Rapanos v. United States, in which the plurality opinion and Justice Kennedy’s concurrence appeared to reflect a limited construction of the term. The following year, in 2015, the District of Maryland came to a similar conclusion in Chevron U.S.A., Inc. v. Apex Oil Co., Inc. The court held that “even if it is hydrologically connected to a body of ‘navigable water,’” groundwater is not regulated under the OPA, also citing the language of the CWA, its legislative history, and Rapanos. Likewise, in 2013, in Tri-Realty Co. v. Ursinus College, the Eastern District of Pennsylvania concluded that “Congress did not intend either the CWA or the OPA to extend federal regulatory authority over groundwater, regardless of whether that groundwater is eventually or somehow ‘hydrologically connected’ to navigable surface waters.”

Other recent district court opinions, however, have come to the opposite conclusion. In 2014, in Hawai’i Wildlife Fund v. County of Maui, the District of Hawaii confronted the issue of whether the County would need a NPDES permit to discharge waste into underground injection wells when plaintiffs contended that some of the injected wastewater eventually finds its way to the Pacific Ocean. The district court concluded that “liability arises even if the groundwater…is not itself protected by the Clean Water Act, as long as the groundwater is a conduit through which pollutants are reaching navigable-in-fact water.” The district court also cited Rapanos in support of its argument. That case is now before the Ninth Circuit on appeal, and the Department of Justice recently filed an amicus brief supporting the argument that there is CWA jurisdiction where pollutants move through groundwater to jurisdictional surface waters if there is a “direct hydrological connection” between the groundwater and surface waters. Likewise, in 2015, in Yadkin Riverkeeper v. Duke Energy Carolinas, LLC, the Middle District of North Carolina held that it had jurisdiction over claims where “pollutants travel from a point source to navigable waters through hydrologically connected groundwater serving as a conduit between the point source and the navigable waters.” That court based its determination in part on the idea that taking an expansive view of the types of discharges which the CWA prohibits is most in line with the statute’s purpose. A few weeks later in Sierra Club v. Virginia Electric and Power Co., the Eastern District of Virginia, citing Yadkin Riverkeeper, held that a CWA citizen suit against Dominion Virginia Power using the conduit theory should survive a motion to dismiss.

The line of cases rejecting CWA jurisdiction over discharges to groundwater which is hydrologically connected to surface waters of the United States gets it right. As the legislative history proves, Congress considered regulating discharges to groundwater and rejected such an approach. This decision is reflected in the language of the statute. Moreover, in Rapanos, the Supreme Court restricted the factual scenarios under which a wetland could be considered a water of the United States, thus revealing that a majority of the justices on the Court favored a narrower jurisdictional reach under the CWA. Finally, to accept the “conduit theory” would be to write the “point source” requirement out of the statute. As described above, a discharge must come from a point source, which the CWA defines as a “discernible, confined and discrete conveyance.” Groundwater seepage seems to be about as far from a “discernible, confined and discrete” source as it gets, resembling nonpoint source pollution like stormwater runoff.

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